CN114944786A - Synchronous motor control method and system - Google Patents

Abstract

The invention discloses a control method and system of a synchronous motor. The control method of a synchronous motor is applied to a control system of a synchronous motor, and the control method of the synchronous motor includes: acquiring a real-time feedback speed of the motor; acquiring a speed setting instruction input by a user; based on the speed setting instruction and the real-time Feedback the rotational speed to determine a speed control command, so that the driving member drives the motor to rotate based on the speed control command; obtains the current running current of the motor; adjusts the speed control command based on the current running current, so that all The driving member drives the motor to rotate based on the adjusted speed control instruction until the difference between the current feedback rotational speeds of the plurality of motors is smaller than a first preset difference. By adopting the above scheme, the balance of the running current of each working motor is ensured, the life of the motor is prolonged, and it can be flexibly applied to different motor coupling control fields without limiting the number of coupled motors.

Description

Synchronous motor control method and system

technical field

Embodiments of the present invention relate to the technical field of motor control, and in particular, to a control method and system for a synchronous motor.

Background technique

Motor coupling control is widely used in the field of asynchronous motors. Multiple asynchronous motors drag the load to run at the same time. Due to the slip of the asynchronous motors, the given control function can be easily realized. In the field of synchronous motors, since there is no influence of slip, the synchronous control of multiple motors requires position feedback from position sensors to achieve corresponding control functions. Because the encoder is expensive and the signal is easily interfered, the coupling control of the synchronous motor can only be used for the synchronous control application of the low-power synchronous motor in the high-precision occasion. In the related art, when multiple motors control a load, the output current of each motor is unbalanced, resulting in different heating of each motor, and a motor with a larger heat generation has a shorter life and is more likely to be damaged than a motor with a smaller heat generation.

SUMMARY OF THE INVENTION

The invention provides a control method and system for a synchronous motor to achieve the effect of prolonging the service life of the motor.

According to an aspect of the present invention, a method for controlling a synchronous motor is provided. The method for controlling a synchronous motor is applied to a control system for a synchronous motor. The control system for a synchronous motor includes a coupling controller, a driver and a motor. The number of the driving member and the motor are multiple, and they are connected in one-to-one correspondence; the coupling controller is electrically connected with the driving member; the control method of the synchronous motor includes:

obtaining the real-time feedback speed of the motor;

Get the speed setting command input by the user;

Determine a speed control command based on the speed setting command and the real-time feedback rotational speed, so that the driving member drives the motor to rotate based on the speed control command;

obtain the current running current of the motor;

The speed control command is adjusted based on the current operating current, so that the driving member drives the motor to rotate based on the adjusted speed control command, until the difference between the current feedback rotational speeds of the plurality of motors is less than the first preset difference;

The speed control command is increased based on the difference between the current feedback rotational speed of the motor and the speed control command, so that the driving member drives the motor to rotate based on the increased speed control command until the The difference between the speed setting command and the real-time feedback rotational speed is smaller than the second preset difference.

In an optional embodiment of the present invention, the adjusting the speed control command based on the current operating current includes:

The speed control command is adjusted in negative feedback based on the current operating current.

In an optional embodiment of the present invention, the adjusting the speed control command in the form of negative feedback based on the current operating current includes:

Based on the current operating current, the speed control command is reduced by a preset amount through the following formula:

F=I*K;

Among them, I is the current running current; K is the reduction ratio; F is the preset reduction range.

In an optional embodiment of the present invention, the determining a speed control command based on the speed setting command and the real-time feedback rotational speed includes:

determining the speed difference between the speed setting command and the real-time feedback speed;

A speed control command is determined by a PID control algorithm based on the speed difference.

In an optional embodiment of the present invention, the expression of the PID control algorithm is:

Among them, Kp is the proportional constant, Ti is the integral time constant, Td is the differential time constant, u(t) is the output signal of the PID control algorithm, and e(t) is the speed difference.

In an optional embodiment of the present invention, the driving member includes a frequency converter;

The acquiring the real-time feedback speed of the motor includes:

Obtain the real-time feedback speed of the motor estimated by the inverter.

In an optional embodiment of the present invention, the determining a speed control command based on the speed setting command and the real-time feedback rotational speed, so that the driving member drives the motor to rotate based on the speed control command, comprising:

Determine a speed control command based on the speed setting command and the real-time feedback rotational speed, so that the frequency converter drives the motor to rotate based on the output drive frequency of the speed control command;

Correspondingly, the adjusting the speed control instruction based on the current operating current, so that the driving member drives the motor to rotate based on the adjusted speed control instruction, including:

The speed control command is adjusted based on the current running current, so that the frequency converter drives the motor to rotate based on the adjusted output drive frequency of the speed control command.

According to another aspect of the present invention, a control system for a synchronous motor is provided, the control system for the synchronous motor includes a coupling controller, a driving member and a motor;

The number of the driving member and the motor are multiple, and they are connected in one-to-one correspondence, and the driving member is used to drive the motor to rotate;

the coupling controller is electrically connected to the driving member;

The coupling controller is used to execute the control method for a synchronous motor according to any embodiment of the present invention.

In an optional embodiment of the present invention, the driving member includes a frequency converter;

The frequency converter is used for outputting a driving frequency to drive the motor to rotate; and/or the frequency converter is used for estimating the real-time feedback speed of the motor.

In an alternative embodiment of the present invention, the coupling controller comprises a PLC.

The technical solution of the embodiment of the present invention is to obtain the real-time feedback speed of the motor; obtain the speed setting instruction input by the user; The speed control instruction drives the motor to rotate; further obtains the current operating current of the motor; adjusts the speed control instruction based on the current operating current, so that the driving member drives based on the adjusted speed control instruction The motor rotates until the difference between the current feedback rotational speeds of a plurality of the motors is less than a first preset difference; finally, the speed is increased based on the difference between the current feedback rotational speed of the motors and the speed control command a control instruction, so that the driving member drives the motor to rotate based on the increased speed control instruction until the difference between the speed setting instruction and the real-time feedback rotational speed is smaller than a second preset difference. It can make the speed control command change according to the current running current of the motor, and then the load of each motor will tend to be balanced, which solves the phenomenon that the output current of each motor is unbalanced when multiple motors control the load, resulting in different heating of each motor. , the motor with more heat is shorter than the motor with less heat and is easily damaged, which ensures the balance of the running current of each working motor and prolongs the life of the motor. It can be flexibly used in different motor coupling control fields, and the number of coupled motors is not limited.

It should be understood that the content described in this section is not intended to identify key or critical features of the embodiments of the invention, nor is it intended to limit the scope of the invention. Other features of the present invention will become readily understood from the following description.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

FIG. 1 is a structural block diagram of a control system for a synchronous motor to which a method for controlling a synchronous motor according to Embodiment 1 of the present invention is applied;

FIG. 2 is a flowchart of a method for controlling a synchronous motor according to Embodiment 1 of the present invention;

3 is a structural block diagram of another synchronous motor control system to which the synchronous motor control method provided in the first embodiment of the present invention is applied;

FIG. 4 is a flowchart of a method for controlling a synchronous motor according to Embodiment 2 of the present invention.

Among them: 1. Coupling controller; 2. Driving part; 21. Frequency converter; 3. Motor.

Detailed ways

In order to make those skilled in the art better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only Embodiments are part of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that the terms "first", "second" and the like in the description and claims of the present invention and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific sequence or sequence. It is to be understood that the data so used may be interchanged under appropriate circumstances such that the embodiments of the invention described herein can be practiced in sequences other than those illustrated or described herein. Furthermore, the terms "comprising" and "having" and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those expressly listed Rather, those steps or units may include other steps or units not expressly listed or inherent to these processes, methods, products or devices.

Example 1

FIG. 1 is a structural block diagram of a control system of a synchronous motor to which a method for controlling a synchronous motor provided by Embodiment 1 of the present invention is applied, and FIG. 2 is a flowchart of a control method of a synchronous motor provided by Embodiment 1 of the present invention, This embodiment is applicable to the case of coupling control of multiple motors, and the control method of a synchronous motor is applied to a control system of a synchronous motor. As shown in FIG. 1 , the control system of a synchronous motor includes a coupling controller, a driver and a The number of the motor, the driving member and the motor are multiple, and they are connected in one-to-one correspondence; the coupling controller is electrically connected with the driving member. The input of the coupling controller is the real-time feedback speed of the motor and the speed setting command input by the user, and the output of the coupling controller is the input of the driving element. A driver drives the motor to rotate based on the input. In this embodiment, the control method for a synchronous motor can be applied to a coupling controller, and the coupling controller executes the control method for a synchronous motor by means of hardware and/or software. As shown in Figure 2, the control method of the synchronous motor includes:

S110. Acquire the real-time feedback speed of the motor.

The real-time feedback speed of the motor refers to the actual speed value of the motor in the current running state.

S120. Acquire a speed setting instruction input by the user.

The speed setting instruction input by the user refers to the speed value that the motor should reach as set by the user.

S130. Determine a speed control command based on the speed setting command and the real-time feedback rotational speed, so that the driving member drives the motor to rotate based on the speed control command.

Wherein, the speed control command refers to a command that instructs the rotational speed that the driving element drives the motor to reach. Since the number of the driving members is multiple, each driving member controls the correspondingly connected motor to run at the rotation speed corresponding to the speed control command according to the speed control command.

S140. Obtain the current running current of the motor.

Among them, the current running current refers to the current when the current motor is running. When multiple motors are controlling the load, the current operating current of each motor will be different.

S150. Adjust the speed control command based on the current operating current, so that the driving member drives the motor to rotate based on the adjusted speed control command, until the difference between the current feedback rotational speeds of the plurality of motors is less than The first preset difference.

The current feedback speed refers to the current actual speed of the motor. When the loads of the motors tend to be balanced, the actual speeds of the motors tend to be equal, that is, the difference between the current feedback speeds of the plurality of motors is smaller than the first preset speed. Set the difference.

When the driver controls the correspondingly connected motors to run according to the speed control command, the speed control commands received by each motor are the same, but the current running current will be different. At this time, the corresponding speed control command is adjusted by the current running current of each motor, so that the speed control command can be changed according to the current running current of the motor, and the load of each motor will tend to be balanced, thereby prolonging the effect of the service life of the motor.

S160. Increase the speed control command based on the difference between the current feedback rotational speed of the motor and the speed control command, so that the driving member drives the motor to rotate based on the increased speed control command, until The difference between the speed setting command and the real-time feedback rotational speed is smaller than a second preset difference.

Among them, through the above continuous adjustment process, the load of each motor is finally balanced. In this process, the increase of the current will cause the motor running speed to drop, and the actual load speed will be less than the set speed, that is, the speed of each motor will be lower than the set speed. When the load tends to balance, the current feedback speed of the motor will be less than the speed setting command. At the same time, due to the requirement of accuracy, the actual load speed and the set speed are difficult to be completely consistent, and there will be a certain fluctuation. When the difference between the speed setting command and the real-time feedback speed is less than the second preset difference, the description The difference between the speed setting command and the real-time feedback rotational speed is small and tends to be consistent. The size of the second preset difference reflects the control accuracy, which is not specifically limited here, and can be set according to usage requirements.

Since the current feedback speed of the motor will be less than the speed setting command when the loads of the motors tend to be balanced, the speed control command is increased based on the difference between the current feedback speed of the motor and the speed control command. , so that the driving element drives the motor to rotate based on the increased speed control command, so that the actual load speed is consistent with the set speed, and the final control purpose is achieved.

For example, in a specific embodiment, it is assumed that the speed setting command is 1000 revolutions. At this time, the speed control command will control the driving element to drive the motor to rotate at a requirement of 1000 revolutions. Then, during the rotation of the motor, due to the unbalanced load , the speed and current of different motors will be different. At this time, after continuous adjustment, the load will be in a balanced state. However, when the load of each motor tends to be balanced, the current feedback speed of the motor will be less than the speed setting command. The motor is probably stable at around 950 rpm. It means that when a command of 1000 rpm is required to send a speed control command, the actual speed when the load is balanced, that is, the current feedback speed can only be around 950 rpm, which cannot achieve the control purpose. At this time, the speed control command is increased based on the difference between the current feedback speed and the speed control command, that is, the speed control command is increased by 50 revolutions based on the difference between 1000 revolutions and 950 revolutions, so that it sends a command of 1050 revolutions to control the drive at 1050 revolutions. The motor is driven to rotate, so that when the load of each motor tends to be balanced, the motor can reach 1000 revolutions of the speed setting command to achieve the final control purpose.

In the above scheme, the real-time feedback speed of the motor is obtained; the speed setting instruction input by the user is obtained; the speed control command is determined based on the speed setting command and the real-time feedback speed, so that the driver is based on the speed control command driving the motor to rotate; further obtaining the current operating current of the motor; adjusting the speed control instruction based on the current operating current, so that the driving member drives the motor to rotate based on the adjusted speed control instruction, Until the difference between the current feedback rotational speeds of the plurality of motors is less than the first preset difference; finally, the speed control command is increased based on the difference between the current feedback rotational speed of the motors and the speed control command, so that the speed control command is increased. The driving member drives the motor to rotate based on the increased speed control command until the difference between the speed setting command and the real-time feedback rotational speed is less than a second preset difference. It can make the speed control command change according to the current running current of the motor, and then the load of each motor will tend to be balanced, which solves the phenomenon that the output current of each motor is unbalanced when multiple motors control the load, resulting in different heating of each motor. , the motor with more heat is shorter than the motor with less heat and is easily damaged, which ensures the balance of the running current of each working motor and prolongs the life of the motor. It can be flexibly used in different motor coupling control fields, and the number of coupled motors is not limited.

In an optional embodiment of the present invention, the determining a speed control command based on the speed setting command and the real-time feedback rotational speed includes:

A speed difference between the speed setting command and the real-time feedback rotational speed is determined.

A speed control command is determined by a PID control algorithm based on the speed difference.

Among them, the speed difference value reflects the deviation between the actual speed value of the motor in the current running state and the speed value that the motor should reach as set by the user.

PID is the abbreviation of Proportional (proportional), Integral (integral) and Differential (differential). As the name suggests, PID control algorithm is a control algorithm that combines proportional, integral and differential links. It is the most mature and widely used control algorithm in continuous systems. This control algorithm appeared in the 1930s and 1940s. , which is suitable for occasions when the controlled object model is unclear. The actual operation experience and theoretical analysis show that, when using this control law to control many industrial processes, satisfactory results can be obtained. The essence of PID control is to perform operations according to the functional relationship of proportional, integral and differential according to the input deviation value, and the operation results are used to control the output.

Therefore, through the PID control algorithm, if the load of the motor increases, the motor speed decreases, and the deviation between the speed setting command and the real-time feedback speed increases (that is, the speed difference increases), so that the speed control command of the driver increases, increasing Increase the motor speed, thereby reducing the deviation between the speed setting command and the real-time feedback speed. If the load of the motor decreases, the motor speed increases, the deviation between the speed setting command and the real-time feedback speed decreases (that is, the speed difference decreases), and the speed control command through the coupling controller decreases, reducing the motor speed, thereby Reduce the deviation between the speed setting command and the real-time feedback speed. After continuous adjustment, the real-time feedback speed approaches the speed setting command. So as to achieve the purpose of controlling the motor speed.

Exemplarily, the expression of the PID control algorithm is:

Among them, Kp is the proportional constant, Ti is the integral time constant, Td is the differential time constant, u(t) is the output signal of the PID control algorithm, and e(t) is the speed difference.

Among them, the output signal of the PID control algorithm is the current control command. Through the above expression, the current control command can be conveniently determined according to the speed difference, thereby realizing the control of the motor speed.

In an alternative embodiment of the present invention, as shown in FIG. 3 , the driving member (not shown in FIG. 3 ) includes a frequency converter.

The acquiring the real-time feedback rotational speed of the motor includes: acquiring the real-time feedback rotational speed of the motor estimated by a frequency converter.

Among them, a variable-frequency drive (VFD) is a power control device that uses frequency conversion technology and microelectronic technology to control the AC motor by changing the frequency of the working power supply of the motor. The main circuit of the inverter can be roughly divided into two categories: the voltage type is the inverter that converts the DC of the voltage source into the AC, and the filter of the DC circuit is the capacitor. The current type is a frequency converter that converts the DC of the current source into an AC, and its DC loop filter is an inductance.

Since the speed of the motor has a certain relationship with the frequency, the formula of the speed of the motor and the frequency is: n=60f/p, and when the inverter drives the motor to rotate, it will change the working power frequency of the motor, so the inverter can estimate the speed of the motor, that is, real-time Feedback speed.

In the above scheme, the real-time feedback speed of the motor estimated by the frequency converter is obtained, and then the speed setting instruction input by the user is obtained; the speed control instruction is determined based on the speed setting instruction and the real-time feedback speed, so that the driving element is based on the The speed control instruction drives the motor to rotate; obtains the current operating current of the motor; and finally adjusts the speed control instruction based on the current operating current, so that the driver drives the motor based on the adjusted speed control instruction The motor turns. In this way, the speed loop can be completed through the coupling controller, and the result after the PID operation can be used as the input of the current loop formed by the inverter. The problem of conflict between motor speeds that may be caused by loop work is solved, thereby solving the coupling control of multiple motors without position sensors, reducing the cost of coupling control and increasing the reliability of the system. At the same time, it can also make the actual load speed consistent with the set speed, so as to achieve the final control purpose.

On the basis of the above embodiment, determining a speed control command based on the speed setting command and the real-time feedback rotational speed, so that the driving member drives the motor to rotate based on the speed control command, includes:

A speed control command is determined based on the speed setting command and the real-time feedback rotational speed, so that the frequency converter outputs a drive frequency based on the speed control command to drive the motor to rotate.

Among them, because the motor speed and frequency have a certain relationship, the formula of motor speed and frequency: n=60f/p, and when the inverter drives the motor to rotate, the working power frequency of the motor will change, so the inverter outputs the corresponding output based on the speed control command. The drive frequency can make the motor rotate, and the speed of the motor can be adjusted by adjusting the output drive frequency.

On the basis of the above embodiment, the adjusting the speed control command based on the current operating current, so that the driving member drives the motor to rotate based on the adjusted speed control command, including:

The speed control command is adjusted based on the current running current, so that the frequency converter drives the motor to rotate based on the adjusted output drive frequency of the speed control command.

The frequency converter adjusts the speed of the motor by adjusting the drive frequency, so after the speed control command is adjusted, the frequency converter outputs the drive frequency based on the adjusted speed control command, so that the speed of the motor can be changed.

Embodiment 2

4 is a flowchart of a method for controlling a synchronous motor according to Embodiment 2 of the present invention. Embodiment 2 is improved on the basis of Embodiment 1. Optionally, the The speed control command includes: adjusting the speed control command in the form of negative feedback based on the current operating current. As shown in Figure 4, the control method of the synchronous motor includes:

S210. Acquire the real-time feedback speed of the motor.

S220. Acquire the speed setting instruction input by the user.

S230. Determine a speed control command based on the speed setting command and the real-time feedback rotational speed, so that the driving member drives the motor to rotate based on the speed control command.

S240. Obtain the current running current of the motor.

S250. Adjust the speed control command in the form of negative feedback based on the current operating current, so that the driving member drives the motor to rotate based on the adjusted speed control command until the current feedback rotational speed of the motors is reached The difference is smaller than the first preset difference.

Among them, the negative feedback means that the current running current superimposed on the speed control command will weaken the speed control command, and when the current running current is larger, the speed control command will decrease more.

S260. Increase the speed control command based on the difference between the current feedback rotational speed of the motor and the speed control command, so that the driving member drives the motor to rotate based on the increased speed control command, until The difference between the speed setting command and the real-time feedback rotational speed is smaller than a second preset difference.

In the above solution, when the speed setting command is manually set, the speed control command currently sent to each driving element is calculated according to the speed setting command and the real-time feedback rotational speed. Multiple drives control the speed corresponding to the motor running speed control command according to the issued speed control command. At this time, the speed of multiple motors is the same, but the current is different.

According to the running current of multiple motors, the current running current of the motor is superimposed on the respective speed control commands in the form of negative feedback. When the current of a motor increases, its actual speed control command will decrease. The other motor speed control commands remain unchanged, the motor speed is reduced, so the actual load of the motor will be reduced, so that the current of the motor will be reduced.

The speed reduction of multiple motors with the largest load is the largest, and the reduction of small loads is smaller. Through the continuous adjustment process, the loads of multiple motors will eventually tend to balance. But this is due to the decrease of the motor running speed caused by the increase of current, which will make the actual load speed less than the set speed. At this time, according to the magnitude of load reduction, that is, the difference between the speed setting command and the real-time feedback speed, the speed reference of the entire system is increased again, so that the actual load speed is consistent with the set speed, and the final control purpose is achieved.

In an optional embodiment of the present invention, the adjusting the speed control command in the form of negative feedback based on the current operating current includes:

Based on the current operating current, the speed control command is reduced by a preset amount through the following formula:

F=I*K.

Among them, I is the current running current; K is the reduction ratio; F is the preset reduction range.

Among them, in this way, the amplitude of the speed control command with heavier load decreases more, the decrease of the speed control command makes the load lighter, and the amplitude of the speed control command with a light load decreases lower, and continuous adjustment can make the speed control between multiple motors. current balance.

In addition, in a specific embodiment, when the driving component is a frequency converter, because the frequency converter changes the motor speed by changing the frequency, K is the frequency reduction ratio of the set parameter, and F is the frequency reduction amplitude.

Embodiment 3

Embodiment 3 of the present invention discloses a control system for a synchronous motor. As shown in FIG. 1 , the control system for a synchronous motor includes a coupling controller 1 , a driving member 2 and a motor 3 .

The number of the driving member 2 and the motor 3 is multiple, and they are connected in one-to-one correspondence, and the driving member 2 is used to drive the motor 3 to rotate.

The coupling controller 1 is electrically connected to the driving member 2, and the coupling controller 1 is used to execute the control method of the synchronous motor according to any embodiment of the present invention.

The input of the coupling controller is the real-time feedback speed of the motor and the speed setting command input by the user, and the output of the coupling controller is the input of the driving element. The driver drives the motor to rotate based on the input.

In the above scheme, by setting the coupling controller 1 and the driving member 2, and making the coupling controller 1 and the driving member 2 electrically connected, the coupling controller 1 obtains the real-time feedback speed of the motor 3; obtains the speed setting instruction input by the user; and then based on the speed Set the command and the real-time feedback speed to determine the speed control command, so that the driver 2 drives the motor 3 to rotate based on the speed control command; finally obtain the current operating current of the motor 3; The subsequent speed control command drives the motor 3 to rotate until the difference between the current feedback rotational speeds of the plurality of motors 3 is less than the first preset difference; the speed control command is increased based on the difference between the current feedback rotational speed of the motors 3 and the speed control command, to The driving member 2 drives the motor 3 to rotate based on the increased speed control command until the difference between the speed setting command and the real-time feedback rotational speed is smaller than the second preset difference. The balance of the running current of each working motor 3 is ensured, and the life of the motor 3 is prolonged. It can be flexibly applied in different fields of motor 3 coupling control, and the number of coupled motors 3 is not limited.

In an optional embodiment of the present invention, the coupling controller 1 is further configured to adjust the speed control command in the form of negative feedback based on the current operating current.

On the basis of the above-mentioned embodiment, the coupling controller 1 is further configured to reduce the speed control command by a preset magnitude by using the following formula based on the current operating current:

F=I*K.

Among them, I is the current running current; K is the reduction ratio; F is the preset reduction range.

In an optional embodiment of the present invention, the coupling controller 1 is further configured to determine the speed difference between the speed setting command and the real-time feedback rotational speed; and determine the speed control command through a PID control algorithm based on the speed difference.

Exemplarily, the expression of the PID control algorithm is:

Among them, Kp is the proportional constant, Ti is the integral time constant, Td is the differential time constant, u(t) is the output signal of the PID control algorithm, and e(t) is the speed difference.

In an optional embodiment of the present invention, as shown in FIG. 3 , the driving element 2 (not shown in FIG. 3 ) includes a frequency converter 21 , and the frequency converter 21 is also used for estimating the real-time feedback speed of the motor 3 ; the coupling controller 1 It is also used to obtain the real-time feedback speed of the motor 3 estimated by the inverter 21 . Among them, the frequency converter 21 (Variable-frequency Drive, VFD) is a power control device that uses frequency conversion technology and microelectronic technology to control the AC motor by changing the working power frequency of the motor 3 . The main circuit of the frequency converter 21 can be roughly divided into two categories: the voltage type is the frequency converter 21 which converts the DC of the voltage source into the AC, and the filter of the DC circuit is the capacitor. The current type is the inverter 21 that converts the DC of the current source into the AC, and its DC loop filter is an inductance.

Since the rotational speed of the motor 3 has a certain relationship with the frequency, the formula of the rotational speed and frequency of the motor 3 is: n=60f/p, and the frequency of the working power supply of the motor 3 will be changed when the frequency converter 21 drives the motor 3 to rotate, so the frequency converter 21 can estimate The rotational speed of the motor 3 is the real-time feedback rotational speed. Since the coupling controller 1 is electrically connected to the driving element 2 , the coupling controller 1 can obtain the real-time feedback rotational speed estimated by the inverter 21 .

In an alternative embodiment of the invention, the coupling controller 1 comprises a PLC.

Among them, PLC (Programmable Logic Controller) refers to a programmable logic controller, and a programmable logic controller is a digital operation operating electronic system specially designed for application in an industrial environment. It uses a programmable memory to store instructions for performing operations such as logic operations, sequence control, timing, counting and arithmetic operations, and controls various types of mechanical equipment or production through digital or analog input and output. process. Therefore, by making the coupling controller 1 include a PLC, the control method for a synchronous motor described in any embodiment of the present invention can be conveniently executed, so as to realize the coupling control of the plurality of motors 3 .

Note that the above are only preferred embodiments of the present invention and applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments herein, and various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present invention. The scope is determined by the scope of the appended claims.

Claims (10)

1. The control method of the synchronous motor is characterized by being applied to a control system of the synchronous motor, wherein the control system of the synchronous motor comprises a coupling controller, a driving part and a plurality of motors, and the driving part and the motors are respectively connected in a one-to-one correspondence manner; the coupling controller is electrically connected with the driving piece; the control method of the synchronous motor comprises the following steps:

acquiring a real-time feedback rotating speed of the motor;

acquiring a speed setting instruction input by a user;

determining a speed control instruction based on the speed setting instruction and the real-time feedback rotating speed so that the driving piece drives the motor to rotate based on the speed control instruction;

acquiring the current running current of the motor;

adjusting the speed control instruction based on the current running current so that the driving part drives the motors to rotate based on the adjusted speed control instruction until the difference value of the current feedback rotating speeds of the motors is smaller than a first preset difference value;

and increasing the speed control instruction based on the difference value between the current feedback rotating speed of the motor and the speed control instruction so as to enable the driving part to drive the motor to rotate based on the increased speed control instruction until the difference value between the speed setting instruction and the real-time feedback rotating speed is smaller than a second preset difference value.

2. The method of controlling a synchronous machine according to claim 1, wherein said adjusting the speed control command based on the present operating current comprises:

adjusting the speed control command in a negative feedback form based on the current operating current.

3. The method of claim 2, wherein said adjusting the speed control command in a negative feedback fashion based on the current operating current comprises:

reducing the speed control command by a preset magnitude based on the current operating current by:

F＝I*K；

wherein I is the current operating current; k is a reduction ratio; f is a predetermined magnitude of the decrease.

4. The control method of a synchronous machine according to any one of claims 1 to 3, wherein said determining a speed control command based on said speed setting command and said real-time feedback rotational speed comprises:

determining a speed difference value between the speed setting instruction and the real-time feedback rotating speed;

and determining a speed control command through a PID control algorithm based on the speed difference value.

5. The control method of the synchronous motor according to claim 4, wherein the expression of the PID control algorithm is:

kp is a proportional constant, Ti is an integral time constant, Td is a derivative time constant, u (t) is an output signal of a PID control algorithm, and e (t) is a speed difference value.

6. The control method of a synchronous motor according to any one of claims 1 to 3, characterized in that the drive member includes a frequency converter;

the acquiring of the real-time feedback rotating speed of the motor comprises the following steps:

and acquiring the real-time feedback rotating speed of the motor estimated by the frequency converter.

7. The method of claim 6, wherein the determining a speed control command based on the speed setting command and the real-time feedback rotational speed to cause the driving member to drive the motor to rotate based on the speed control command comprises:

determining a speed control instruction based on the speed setting instruction and the real-time feedback rotating speed so that the frequency converter outputs a driving frequency based on the speed control instruction to drive the motor to rotate;

correspondingly, the adjusting the speed control command based on the current running current to enable the driving part to drive the motor to rotate based on the adjusted speed control command includes:

and adjusting the speed control instruction based on the current running current so that the frequency converter outputs a driving frequency based on the adjusted speed control instruction to drive the motor to rotate.

8. A control system of a synchronous machine, characterized in that it comprises a coupling controller (1), a drive (2) and a motor (3);

the number of the driving pieces (2) and the number of the motors (3) are multiple, the driving pieces (2) are connected in a one-to-one correspondence manner, and the motors (3) are driven to rotate by the driving pieces (2);

the coupling controller (1) is electrically connected with the driving piece (2);

the coupling controller (1) is adapted to perform the method of controlling a synchronous machine according to any of claims 1-7.

9. Control system of a synchronous machine according to claim 8, characterized in that the drive (2) comprises a frequency converter (21);

the frequency converter (21) is used for outputting a driving frequency to drive the motor (3) to rotate; and/or the frequency converter (21) is used for estimating the real-time feedback rotating speed of the motor (3).

10. Control system of a synchronous machine according to claim 8 or 9, characterized in that the coupling controller (1) comprises a PLC.

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